Surgical instrumentation and method

ABSTRACT

A surgical instrument includes a first member having an inner surface and an outer surface. A second member has an inner surface and an outer surface. At least one of the inner surfaces defines at least one mating element and the outer surfaces are engageable with tissue. The members are relatively movable between a first configuration and a second configuration to space the tissue and define an opening between the members. At least one third member defines at least one mating element engageable with the at least one mating element of the inner surface such that the at least one third member is disposed within the opening. Systems and methods are disclosed.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 14/219,821, filed Mar. 19, 2014, which is incorporated byreference herein, in its entirety.

TECHNICAL FIELD

The present disclosure generally dates to medical devices for thetreatment of musculoskeletal disorders, and more particularly to asurgical system and a method for treating a spine.

BACKGROUND

Spinal pathologies and disorders such as scoliosis and other curvatureabnormalities, kyphosis, degenerative disc disease, disc herniation,osteoporosis, spondylolisthesis, stenosis, tumor, and fracture mayresult from factors including trauma, disease and degenerativeconditions caused by injury and aging. Spinal disorders typically resultin symptoms including deformity, pain, nerve damage, and partial orcomplete loss of mobility.

Non-surgical treatments, such as medication, rehabilitation and exercisecan be effective, however, may fail to relieve the symptoms associatedwith these disorders. Surgical treatment of these spinal disordersincludes fusion, fixation, correction, discectomy, laminectomy,corpectomy and implantable prosthetics. As part of these surgicaltreatments, spinal constructs, such as, for example, bone fasteners,spinal rods and interbody devices can be used to provide stability to atreated region. For example, during surgical treatment, surgicalinstruments can be used to deliver component of the spinal constructs tothe surgical site for fixation with bone to immobilize a joint. Certainspinal surgery approaches utlize a direct lateral approach to accesslumbar disc spaces, however, these techniques present certain thallengesdue to the location of musculature and neural structures embeddedtherein.

This disclosure describes an improvement over these prior arttechnologies with the provision of specialized instrumentation, implantsand techniques to allow for a surgical pathway to the lumbar discspaces.

SUMMARY

Systems and methods of use for accessing disc spaces are provided. Insome embodiments, a surgical instrument is provided. The surgicalinstrument includes a first member having an inner surface and an outersurface. A second member has an inner surface and an outer surface. Atleast one of the inner surfaces defines at least one mating element andthe outer surfaces are engageable with tissue. The members arerelatively movable between a first configuration and a secondconfiguration to space the tissue and define an opening between themembers. At least one third member defines at least one mating elementengageable with the at least one mating element of the inner surfacesuch at the at least one third member is disposed within the opening.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure will become more readily apparent from thespecific description accompanied by the following drawings, in which:

FIG. 1 is a perspective view of components of one embodiment of a systemin accordance with the principles of the present disclosure;

FIG. 2 is a break away, plan view of the components shown in FIG. 1;

FIG. 3 is a break away, plan view of the components shown in FIG. 1;

FIG. 4 is an axial view of a component of one embodiment of a system inaccordance with the principles of the present disclosure disposed withvertebrae;

FIG. 5 is a perspective view of the component and vertebrae show in FIG.4;

FIG. 6 is a side view of the component and vertebrae shown in FIG. 4:

FIG. 7 is an axial view of components of one embodiment of a system inaccordance with the principles of the present disclosure disposed withvertebrae;

FIG. 8 is a perspective view of the components and vertebrae shown inFIG. 7;

FIG. 9 is a side view of the components and vertebrae shown in FIG. 7;

FIG. 10 is an axial view of the components and vertebrae shown in FIG.7;

FIG. 11 is a perspective view of the components and vertebrae shown inFIG. 7;

FIG. 12 is a side view of the components and vertebrae shown in FIG. 7;

FIG. 13 is a perspective view of components and the vertebrae shown inFIG. 7;

FIG. 14 is a side view of the components and vertebra shown in FIG. 13;

FIG. 15 is a perspective view of components of one embodiment of asystem in accordance with the principles of the present disclosuredisposed with vertebrae;

FIG. 16 is a side view of the components and vertebrae shown in FIG. 15;

FIG. 17 is an axial view of the components and vertebrae shown in FIG.15;

FIG. 18 is a perspective view of e components and vertebrae shown inFIG. 15;

FIG. 19 is a side view of the components and vertebrae shown in FIG. 15;

FIG. 20 is a side view of the components and vertebrae shown in FIG. 15;

FIG. 21 is a perspective view of components and vertebrae shown in FIG.15;

FIG. 22 is a side view of one embodiment of the components and vertebraeshown in FIG. 15;

FIG. 23 is a break away plan view of components of one embodiment of asystem in accordance with the principles of the present disclosure;

FIG. 24 is a perspective view of components of the system shown in FIG.23;

FIG. 25 is a perspective view of components of the system shown in FIG.23;

FIG. 26 is a perspective view of components of the system shown in FIG.23;

FIG. 27 is a break away plan view of components of the system shown inFIG. 23;

FIG. 28 is a perspective view of components of one embodiment of asystem in accordance with the principles of the present disclosure;

FIG. 29 is a perspective view of components of the system shown in FIG.28;

FIG. 30 is a perspective view of components of the system shown in FIG.28; and

FIG. 31 is a break away plan view of components of the system shown inFIG. 28.

DETAILED DESCRIPTION

The exemplary embodiments of the surgical system and related methods ofuse disclosed are discussed in terms of medical devices for thetreatment of musculoskeletal disorders and more particularly, in termsof a surgical system for implant delivery to a surgical site and amethod for treating a spine. In one embodiment, the systems and methodsof the present disclosure are employed with a spinal joint and fusion,for example, with a cervical, thoracic, lumbar and/or sacral region of aspine.

In one embodiment, the surgical system includes a surgical instrument,such as, for example, a retractor having interlocking blades. In someembodiments, the retractor includes retractor blades and one or aplurality of interlocking blades attachable therewith. In someembodiments, the retractor blades include one or more grooves such thatan interlocking blade can be translated to close and/or partially closea gap of the retractor blades. In some embodiments, an anterior portionof the retractor blades includes a groove such that an interlockingblade is slid along the groove and into position to close an anteriorgap between the retractor blades. In some embodiments, a posteriorportion of the retractor blades includes a groove such that aninterlocking blade is slid along the groove and into position to close aposterior gap between the retractor blades.

In some embodiments, the retractor can include interlocking and/orinterleaved blades, for example, in a three blade embodiment thatpartially encloses a surgical pathway and/or corridor, and for example,in a four blade embodiment that fully encloses a surgical pathway and/orcorridor. In some embodiments, the retractor can include one or aplurality of interlocking wedges that connect with the retractor blades.In some embodiments, the interlocking wedges connect with the retractorblades in a dovetail connection. In some embodiments, the retractorincludes a blade having a pin hole on a superior blade disposed adjacentan edge surface. In some embodiments, the retractor can includeinterlocking blades having a variety of widths to accommodate differentretractor openings.

In one embodiment, the surgical system is employed with a methodincluding an oblique lateral interbody fusion (OLIF) procedure in thelower lumbar region between an L1 vertebral body and an L5 vertebralbody using an antero-lateral operative corridor between a posteriorpsoas muscle and an anterior vasculature, such as, for example, the venacava and aorta. In one embodiment, patient is placed on their side, leftside up, to position the vena cava on the right side of a centerline. Inone embodiment, the surgical system displaces the psoas muscleposteriorly thereby avoiding teasing apart the muscle fibers anddisrupting nerves located in the psoas muscle in the L1- L5 vertebralregion. In one embodiment, the psoas muscle is numbed and/or paralyzedduring the surgical procedure.

In one embodiment, the surgical system includes a surgical instrument,such as, for example, a retractor configured for use with an OLIFprocedure for treating the L2-L5 vertebral region. In one embodiment,the surgical system includes non-modular components and/or attachments.In one embodiment, the retractor includes relatively flat blades toallow for plate and screw placement and blade pin placement away from acenter of body/segmental vessels. In one embodiment, the retractorincludes stiff and biased blades. In one embodiment, the retractorincludes blades having an oval blade shape, which facilitates lateralsweeping of the psoas muscle. In one embodiment, the lateral sweepingcan include rotating the blades and/or the oval shaped blade dilator tomove the psoas muscle. In one embodiment, the retractor includes a lightfor visualization of a surgical site.

In one embodiment, the system includes a retractor having a taperedportion to facilitate insertion and displacement of psoas tissue. In oneembodiment, the retractor blades include a lip on an end of theretractor blade. In one embodiment, the lip is configured to be rotatedunder the psoas muscle after the blades are positioned adjacent to thespine. This configuration prevents the psoas muscle from creeping underthe blades.

In one embodiment, the system includes an oval dilator having offsetpassageways to facilitate final positioning of the retractor in ananterior or posterior orientation relative to an initial dilator. In oneembodiment, an end portion of the retractor blades and/or the ovaldilator are concave to facilitate positioning against and/or conformingto a vertebral body.

In one embodiment, the retractor blades are connected with a handle. Inone embodiment, the handle is connected at an angle to the retractorblades so that handles do not interfere with an iliac crest. In oneembodiment, an angled handle connection is configured to force tips ofthe retractor blades to diverge when opened such that the tipscounteract tissues forces that would normally bias the retractor bladesto a closed position. The retractor blades can be configured forinternal rotation when closed such that when they are opened, they areapproximately parallel.

In one embodiment, an initial dilator tip is integrated into the ovaldilator thereby eliminating the initial dilator step. In someembodiments, the initial dilator tip can be disposed centrally or can beoffset to push the final position of the retractor either anterior orposterior from an initial position of tip.

In one embodiment, the handle includes a lock, such as, for example, aratchet. In one embodiment, the ratchet includes a first tooth angledrearward, which locks the retractor blades in a closed position to avoidthe retractor blades from opening prematurely. In one embodiment, theratchet includes a plurality of teeth that are angled such that theyallow for selective opening of the retractor blades while preventing theretractor blades from closing unless the ratchet is disengaged.

In one embodiment, the surgical system is employed with a methodcomprising the step of inserting a first dilator into an intervertebraldisc space along an oblique trajectory located anterior to psoas tissueand posterior to a peritoneum and great vessels. In one embodiment, thefirst dilator includes a nerve integrity monitoring dilator. In oneembodiment, the method includes the step of inserting an oval dilatorover the first dilator with a narrow side of the oval shaped dilatorpositioned against the psoas muscle. In one embodiment, the methodincludes the step of utilizing a central cannulation disposed in theoval dilator to center retractor blades over the first dilator. In oneembodiment, the method includes the step of utilizing an offsetcannulation disposed in the oval dilator to position the bladesposteriorly over the first dilator.

In one embodiment, the method includes the step of rotating the ovaldilator from an initial position to sweep the psoas muscle laterally andloosen its attachments to the spine and displace the psoas muscle in aposterior direction. In one embodiment, the method includes the step ofrotating the oval dilator back to the initial position such that anarrow side of the oval shape of the dilator is positioned against thepsoas muscle. In one embodiment, the method includes the step of placinga retractor over the dilators with a handle in a practitioner's righthand. This configuration places the blades without a pin hole adjacentto the psoas muscle during insertion. In one embodiment, the methodincludes the step of placing a retractor over the dilators with a handlein a practitioner's left hand.

In one embodiment, the method includes the step of inserting theretractor blades with its longitudinal axis in line with a longitudinalaxis of a spine to facilitate placement of the retractor blades inbetween the psoas muscle and the peritoneum and great vessels. In oneembodiment, the method includes the step of rotating the retractor 90degrees such that the retractor blades displace and/or sweep the psoasmuscle posteriorly, for example, similar to the dilator. In oneembodiment, the method includes the step of positioning the retractorsuch that the blades are in contact with an adjacent vertebral body.

In one embodiment, the method includes the step of opening the retractorblades to remove the dilators and/or such that the retractor blades areopened wide enough to allow for plate and/or screw placement. In oneembodiment, the method includes the step of pinning a superiorpositioned blade and/or a cephalad positioned blade to a vertebral body.In one embodiment, the method includes the step of attaching a flexiblearm to the retractor to stabilize the retractor to the surgical table.In one embodiment, the method includes the step of placing a light cablewith the blades and disposing the cables under a boss on a blade arm.

In one embodiment, a surgical pathway is disposed at an angle relativeto a lateral axis of a patient body. In one embodiment, interbodyimplants and instruments are provided that facilitate positioningthrough the surgical pathway. In one embodiment, an interbody implant isdisposed laterally in the disc space. In one embodiment, the interbodyimplant is positioned at an oblique angle relative to a lateral axis ofthe subject body. In one embodiment, the surgical pathway is oriented0-45 degrees relative to a direct lateral axis of a subject body. In oneembodiment, the surgical pathway is oriented 15-30 degrees relative tothe direct lateral axis. In one embodiment, the surgical instruments areequipped with surgical navigation components, such as, for example,emitters mounted with the instruments and adjacent surgical devicesensors employed with surgical navigation, microsurgical and imageguided technologies that may be employed to access, view and repairspinal deterioration or damage. In one embodiment, a trial is utilizedto establish a starting point for insertion of an interbody implant.

In one embodiment, the present disclosure may be employed to treatspinal disorders such as, for example, degenerative disc disease, discherniation, osteoporosis, spondylolisthesis, stenosis, scoliosis andother curvature abnormalities, kyphosis, tumor and fractures. In oneembodiment, the present disclosure may be employed with other osteal andbone related applications, including those associated with diagnosticsand therapeutics. In some embodiments, the disclosed surgical system andmethods may be alternatively employed in a surgical treatment with apatient in a prone, supine position, lateral and/or employ varioussurgical approaches to the spine, including anterior, posterior,posterior mid-line, direct lateral, postero-lateral, and/orantero-lateral approaches, and in other body regions. The presentdisclosure may also be alternatively employed with procedures fortreating the lumbar, cervical, thoracic, sacral and pelvic regions of aspinal column. The system and methods of the present disclosure may alsobe used on animals, bone models and other non-living substrates, suchas, for example, in training, testing and demonstration.

The present disclosure may be understood more readily by reference tothe following detailed description of the embodiments taken inconnection with the accompanying drawing figures, which form a pail ofthis disclosure. It is to be understood that this application is notlimited to the specific devices, methods, conditions or parametersdescribed and/or shown herein, and that the terminology used herein isfor the purpose of describing particular embodiments by way of exampleonly and is not intended to be limiting. Also, in some embodiments, asused in the specification and including the appended claims, thesingular forms “an,” and “the” include the plural, and reference to aparticular numerical value includes at least that particular value,unless the context clearly dictates otherwise. Ranges may be expressedherein as from “about” or “approximately” one particular value and/or to“about” or “approximately” another particular value. When such a rangeis expressed, another embodiment includes from the one particular valueand/or to the other particular value. Similarly, when values areexpressed as approximations, by use of the antecedent “about,” it willbe understood that the particular value forms another embodiment. It isalso understood at all spatial references, such as, for example,horizontal, vertical, top, upper, lower, bottom, left and right, are forillustrative purposes only and can be varied within the scope of thedisclosure. For example, the references “upper” and “lower” are relativeand used only in the context to the other, and are not necessarily“superior” and “inferior”.

Further, as used in the specification and including the appended claims.“treating” or “treatment” of a disease or condition refers to performinga procedure that may include administering one or more drugs to apatient (human, normal or otherwise or other mammal), employingimplantable devices, and/or employing instruments that treat thedisease, such as, for example, micro discectomy instruments used toremove portions bulging or herniated discs and/or bone spurs, in aneffort to alleviate signs or symptoms of the disease or condition.Alleviation can occur prior to signs or symptoms of the disease orcondition appearing, as well as after their appearance. Thus, treatingor treatment includes preventing or prevention of disease or undesirablecondition (e.g., preventing the disease from occurring in a patient, whomay be predisposed to the disease but has not yet been diagnosed ashaving it). In addition, treating or treatment does not require completealleviation of signs or symptoms, does not require a cure, andspecifically includes procedures that have only a marginal effect on thepatient. Treatment can include inhibiting the disease, e.g., arrestingits development, or relieving the disease, e.g., causing regression ofthe disease. For example, treatment can include reducing acute orchronic inflammation; alleviating pain and mitigating and inducingre-growth of new ligament, bone and other tissues; as an adjunct insurgery; and/or any repair procedure. Also, as used in the specificationand including the appended claims, the term “tissue” includes softtissue, ligaments, tendons, cartilage and/or bone unless specificallyreferred to otherwise.

The folio ting discussion includes a description of a surgical systemand related methods of employing the surgical system in accordance withthe principles of the present disclosure. Alternate embodiments are alsodisclosed. Reference is made in detail to the exemplary embodiments ofthe present disclosure, which are illustrated in the accompanyingfigures. Turning to FIGS. 1-3, there are illustrated components of asurgical system, such as, for example, a spinal implant system 10.

The components of spinal implant system 10 can be fabricated frombiologically acceptable materials suitable for medical applications,including metals, synthetic polymers, ceramics and bone material and/ortheir composites. For example, the components of spinal implant system10, individually or collectively, can be fabricated from materials suchas stainless steel alloys, commercially pure titanium, titanium alloys,Grade 5 titanium, super-elastic titanium alloys, cobalt-chrome alloys,stainless steel alloys, super elastic metallic alloys (e.g., Nitinol,super elasto-plastic metals, such as GUM METAL® manufactured by ToyotaMaterial Incorporated of japan), ceramics and composites thereof such ascalcium phosphate (e.g., SKELITE™ manufactured by Biologix Inc,),thermoplastics such as polyaryletherketone (PAEK) includingpolyetheretherketone (PEEK), polyetherketoneketone (PEKK) andpolyetherketone (PEK), carbon-PEEK composites, PEEK-BaSO₄ polymericrubbers, polyethylene terephthalate (PET), fabric, silicone,polyurethane, silicone-polyurethane copolymers, polymeric rubbers,polyolefin rubbers, hydrogels, semi-rigid and rigid materials,elastomers, rubbers, thermoplastic elastomers, thermoset elastomers,elastomeric composites, rigid polymers including polyphenylene,polyamide, polyimide polyetherimide, polyethylene, epoxy, bone materialincluding autograft, allograft, xenograft or transgenic cortical and/orcorticocancellous bone, and tissue growth or differentiation factors,partially resorbable materials, such as, for example, composites ofmetals and calcium-based ceramics, composites of PEEK and calcium basedceramics, composites of PEEK with resorbable polymers, totallyresorbable materials, such as, for example, calcium based ceramics suchas calcium phosphate such as hydroxyapatite (HA), corraline HA, biphasiccalcium phosphate, tricalcium phosphate, or fluorapatite, tri-calciumphosphate (TCP), HA-TCP, calcium sulfate, or other resorbable polymerssuch as polyaetide, polyglycolide, polytymsine carbonate,polycaroplaetohe and their combinations, bocompatible ceramics,mineralized collagen, bioactive glasses, porous metals, bone particles,bone fibers, morselized bone chips, bone morphogenetic proteins (BMP),such as BMP-2, BMP-4, BMP-7, rhBMP-2, or rhBMP-7, demineralized bonematrix (DBM), transforming growth factors (TGF, e.g., TGF-β), osteoblastcells, growth and differentiation factor (GDF), insulin-like growthfactor 1, platelet-derived growth factor, fibroblast growth factor, orany combination thereof.

Various components of spinal implant system 10 may have materialcomposites, including the above materials, to achieve various desiredcharacteristics such as strength, rigidity, elasticity, compliance,biomechanical performance, durability and radiolucency or imagingpreference. The components of spinal implant system 10, individually orcollectively, may also be fabricated from a heterogeneous material suchas a combination of two or more of the above-described materials. Thecomponents of spinal implant system 10 may be monolithically formed,integrally connected or include fastening elements and/or instruments,as described herein.

Spinal implant system 10 is employed, for example, with a fully opensurgical procedure, a minimally invasive procedure, includingpercutaneous techniques, and mini-open surgical techniques to deliverand introduce instrumentation and/or an implant, such as, for example,an interbody implant, at a surgical site within a subject body of apatient, which includes, for example, a spine having vertebrae V (FIG.4). In some embodiments, the implant can include spinal constructs, suchas, for example, interbody devices, cages, bone fasteners, spinal rods,connectors and/or plates.

System 10 includes a surgical instrument, such as, for example, aretractor 12 having a member, such as, for example, a blade 14. Blade 14extends between an end 14 a and an end 14 b, which may comprise a bladetip. Blade 14 includes an inner surface 18 and an outer surface 20configured for engagement with tissue, such as, for example, tissueadjacent vertebrae V. Vertebrae V defines a longitudinal axis X1 (FIG.8).

Retractor 12 includes a member, such as, for example, a blade 18. Blade16 extends between an end 16 a and an end 16 b, which may comprise ablade Blade 16 includes an inner surface 30 and an outer surface 32configured for engagement with tissue, such as, for example, tissueadjacent vertebrae V. In some embodiments, all or only a portion ofblade 14 and/or blade 16 may have various cross-section configurations,such as, for example, arcuate, cylindrical, oblong, rectangular,polygonal, undulating, irregular, uniform, non-uniform, consistent,variable, and/or U-shape.

End 14 b includes a tapered portion, such as, for example, a side taper22 and surface 20 includes a projection, such as, for example, an endlip 26. End 16 b includes a tapered portion, such as, for example, aside taper 34 and surface 32 includes a projection, such as, forexample, an end lip 38. As such, blades 14, 16 can be inserted adjacentto psoas tissue so that tapers 22, 34 facilitate insertion with tissueand/or displace and/or bias the psoas tissue away from a surgicalpathway. As blades 14, 16 are manipulated, as described herein, blades14, 16 displace psoas tissue posteriorly relative to vertebrae V suchthat lips 26, 38 are disposed and/or rotated under psoas tissue andmaintain the psoas tissue from sliding back under ends 14 b, 16 b and/orresist and prevent creeping of the psoas tissue under ends 14 b, 16 b.End 14 b includes a concave tip surface 24 and end 16 b includes aconcave tip surface 36. Surfaces 24, 36 facilitate seating engagementwith tissue of vertebrae V.

Blades 14, 16 are connected with a handle 50 having handles 50 a, 50 b,which facilitate manipulation of retractor 12 between the positions, asdescribed herein, and relative movement of blades 14, 16 between theconfigurations, as described herein. Handles 50 a, 50 b are connectedwith blades 14, 16, respectively, and pivotally connected at a pivot 51such that blade 14 can be rotated about pivot 51, in the direction shownby arrows A in FIG. 1, and blade 16 can be rotated about pivot 51, inthe directions shown by arrows B.

Handle 50 includes a lock, such as, for example, a ratchet 60 configuredto releasably fix handles 50 a, 50 b and blade 14 in a selectedorientation relative to blade 16 to dispose blades in a selectedconfiguration, as described herein. Ratchet 60 includes a rack having alocking element, such as, for example, a plurality of teeth 62 angled ina first direction and engageable with a locking pin 64 of handle 50 bsuch that blades 14, 16 are selectively and/or incrementally adjustableto a selected configuration, as described herein.

Ratchet 60 includes a locking element, such as, for example, a tooth 66angled in a second opposite direction to releasably fix blades 14, 16 ina closed configuration, as described herein. Tooth 66 locks blades inthe closed configuration to resist and/or prevent relative movement ofblades 14, 16 to an open configuration, as described herein. Teeth 62are disposed in an angular orientation such that teeth 62 allow movementof blades 14, 16 to one or more relatively open configurations, asdescribed herein, while resisting and/or preventing blades fromrelatively moving to a relatively dosed configuration unless ratchet 60is disengaged.

In one embodiment, handle 50 is disposed at an angular orientationrelative to blades 14, 16. Disposal of handle 50 relative to blades 14,16 at an angle resists and/or prevents interference with tissue duringmanipulation of retractor such as, for example, handle 50 is configuredto avoid interference with an iliac crest. In one embodiment, handle 50is connected at an angle to force tips of blades 14, 16 to divergeand/or flare outwardly when opened such that the tips counteract tissuesforces that would normally bias the retractor blades to a dosedconfiguration. In one embodiment, handles 50 a, 50 b each include breakaway portions 52 that pivot about a pivot 54 such that portions 52 canrotate to avoid interference with tissue and/or instrumentation.

Blade 14 is movable relative to blade 16 between a closed configuration,as shown for example in FIG. 2, and an open configuration, as shown infor example, in FIG. 3, such that blades 14, 16 are spaced apart todefine a surgical pathway and facilitate spacing of tissue, as describedherein. In a closed configuration, blades 14, 16 are disposed in aninternally rotated orientation and are movable to an open configurationsuch that blades 14, 16 are relatively parallel as a result of theconfiguration of blades 14, 16. In some embodiments, blades 14, 16 maybe disposed in one or a plurality of open configurations of varyingdegrees of spacing of blades 14, 16, and/or configurations between openand closed configurations.

In one embodiment, in the closed configuration, blades 14, 16 aredisposable between a position, as shown for example in FIGS. 15 and 16,such that surfaces 18, 30 define a substantially oval cavity 40 and aposition, as shown for example in FIGS. 17-19, such that blades 14, 16are rotated to space psoas tissue, as described herein. In oneembodiment, in the first position, cavity 40 comprises a substantiallyteardrop configuration. In some embodiments, blades 14, 16 may berotated to one or a plurality of positions in a clockwise and/or acounter-clockwise direction to displace tissue or facilitate a surgicalprocedure, Cavity 40 extends along the length of blades 14, 16 andprovides a pathway for surgical instruments and/or implants. Cavity 40defines a major axis X2 and a minor axis X3.

In an initial position, as shown for example in FIGS. 15 and 16, axis X2is disposed in substantially parallel alignment with axis X1 Blades 14,16 are rotatable from the initial position to a position, as shown forexample in FIGS. 17-19, such that axis X2 is rotated relative to axis X1to space and/or sweep tissue, such as, for example, psoas tissueposteriorly so that blades 14, 16 can be manipulated to an openconfiguration to define and create a working channel 40 a for a surgicalpathway. Rotation of blades 14, 16 causes surfaces 20, 32 to applypressure against psoas tissue to displace psoas muscle, vertebral tissueand/or adjacent tissue posteriorly relative to the spine. In someembodiments, retractor 12 may displace tissue in alternate directions,such as, for example, anteriorly, laterally, caudal and/or cephalad.

System 10 includes a surgical instrument, such as, for example, adilator 94 and a surgical instrument, such as, for example, a dilator80, as shown in FIG. 1. Dilator 88 has an outer surface 84 and includesan oval cross-section configuration. Dilator 80 extends between an end86 and an end 88. Dilator 80 defines a major axis X4 and a minor axisX5, Dilator 80 is disposable between an initial position, as shown forexample in FIGS. 15 and 16, and a position, as shown for example inFIGS. 17-19, such that surface 84 is rotated to space psoas tissue, asdescribed herein. In one embodiment, in the first position, thecross-section of dilator 80 comprises a substantially teardropconfiguration. In some embodiments, dilator 80 may be rotated to one ora plurality of positions in a clockwise and/or a counter-clockwisedirection to displace tissue or facilitate a surgical procedure.

In the initial position, as shown for example in FIGS. 15 and 16, axisX4 is disposed in substantially parallel alignment with axis X1. Dilator80 is rotatable from the initial position to a position, as shown forexample in FIGS. 17-19, such that axis X4 is rotated relative to axis X1to space and/or sweep tissue, such as, for example, psoas tissueposteriorly. Rotation of dilator 80 causes surface 84 to apply pressureagainst psoas tissue to displace psoas muscle, vertebral tissue and/oradjacent tissue posteriorly relative to the spine. In some embodiments,dilator 80 may displace tissue in alternate directions, such as, forexample, anteriorly, laterally, caudal and/or cephalad. In oneembodiment, surface 84 includes a projection, such as, for example, anend lip 98 (FIG. 9). As dilator 80 and/or blades 14, 16 are manipulated,as described herein, dilator 80 and/or blades 14, 16 displace psoastissue posteriorly relative to vertebrae V such that lip 98 is disposedand/or rotated under psoas tissue and maintains the psoas tissue fromsliding back under end 88 and/or resists and prevents creeping of thepsoas tissue under end 88. End 88 includes a concave tip surface 96 thatfacilitates seating engagement with tissue of vertebrae V.

Dilator 80 defines a central cannulation 90 configured for disposal ofdilator 94. In some embodiments, dilator 80 can include an offsetcannulation that communicates with cannulation 90 and facilitates offsettranslation of retractor 12 anteriorly to a final position from aninitial position of dilator 94. In one embodiment, dilator 80 caninclude an offset cannulation that is spaced from cannulation 90 andfacilitates offset translation of retractor 12 posteriorly to a finalposition from an initial position of dilator 94.

In some embodiments, spinal implant system 10 may comprise varioussurgical instruments, such as, for example, drivers, extenders,reducers, spreaders, distracters, damps, forceps, elevators and drills,which may be alternately sized and dimensioned, and arranged as a kit.In some embodiments, spinal implant system 10 may comprise the use ofmicrosurgical and image guided technologies, such as for example,surgical navigation components employing emitters and sensors, which maybe employed to track introduction and/or delivery of the components ofspinal implant system 10 including the surgical instruments to asurgical site. See, for example, the surgical navigation components andtheir use as described in U.S. Pat. Nos. 6,021,343, 6,725,080,6,796,988, the entire contents of each of these references beingincorporated by reference herein.

In one embodiment, in assembly, operation and use, as shown in FIGS.4-22, spinal implant system 10, similar to the systems described herein,is employed with a surgical procedure for treatment of a spinaldisorder, such as those described herein, affecting a section of a spineof a patient. Spinal implant system 10 may also be employed with othersurgical procedures. To treat the affected section of vertebrae V of asubject body, the subject body is disposed in a side orientationrelative to a surgical fixed surface, such as, for example, a surgicaltable configured for supporting the subject body. The subject body isplaced on a side, left side up such that the vena cava, being orientedto the right of a centerline of the subject body, is positioned furtheraway from a surgical pathway PX, as shown in FIG. 4 and describedherein.

The subject body is oriented such that an OLIF procedure can beperformed obliquely in front of a psoas muscle P to provide directaccess to one or more intervertebral spaces of L2-L5 vertebral levels ofvertebrae V while avoiding selected muscular and abdominal anatomicalstructures, such as, for example anterior vasculature. In someembodiments, placement of the subject body on its side facilitatesaccess to surgical pathway PX that is disposed at an oblique angle. Insome embodiments, placement of the subject body on its side facilitatesnatural movement of the abdominal contents away from surgical pathway PXvia the effect of gravity.

In some embodiments, electrodes, such as, for example, electrodes usedwith neural integrity monitoring systems, may not be necessary as thepathway PX may avoid nerve roots as well as the neural structures inpsoas muscle P that are encountered along a lateral approach. In someembodiments, psoas muscle P is completely paralyzed during the surgicalprocedure as there is no need to monitor or locate nerves present inpsoas muscle P as psoas muscle P is avoided along the oblique surgicalpathway PX. Paralyzing psoas muscle P facilitates manipulation and/orretraction of psoas muscle P during the surgical procedure.

The L2 and L5 disc spaces, lower ribs and iliac crest can be marked onthe skin as landmarks. In some embodiments, for example, a singlevertebral level procedure, the subject body is marked 4-10 centimeters(cm) anterior to the midsection of the target disc (or approximately onethird of the distance from the top of the iliac crest to the umbilicus).A 3 cm to 6 cm vertical, horizontal or oblique incision is made intissue of the subject body. In some embodiments, for example, a twovertebral level procedure, the subject body is marked 4-10 cm anteriorto the midsection of the intervening vertebral body and an incision ismade in tissue of the subject body. In one embodiment, the lumbarlordosis of the operative levels can be marked on the skin to determinethe angle in line with the disc space.

In some embodiments, the subcutaneous fat layers are dissected until theabdominal musculature is reached. In some embodiments, a mono-polarcautery can be utilized for hemostasis, and a small self-retainingretractor can be used for initial dissection of the skin andsubcutaneous layer. In some embodiments, the external oblique fascia isthe first plane encountered and is the only layer that will need to besharply incised. In some embodiments, a damp is used to bluntly spreadthrough the fibers of the external oblique, internal oblique, andtransversalis muscles. In some embodiments, dissection is performed inline with the muscle fibers as these muscle layers extend in oppositedirections.

In some embodiments, an index finger is utilized to follow the internalabdominal wall posteriorly down to psoas muscle P. In some embodiments,a finger or a blunt instrument is used to sweep the peritoneal contents,including the ureter, which reflects with the peritoneum, and theretroperitoneal fat anteriorly past the anterior portion of psoas muscleP clearing to the anterior vertebral body.

Dilator 94 is initially inserted into the disc space between vertebra V1and vertebra V2 along an oblique trajectory along surgical pathway PX,as shown in FIGS. 4-6, anterior relative to psoas muscle P and posteriorto a peritoneum (not shown), Dilator 80 is inserted over dilator 94 suchthat axis X4 of dilator 80 is aligned with axis X1, as shown in FIGS.7-9, In some embodiments, as shown in FIG. 9, dilator 94 is disposedwith offset cannulation 92 for translation, as described herein. In someembodiments, dilator 94 is disposed with center cannulation 90 for acentered alignment over dilator 94.

Dilator 80 is rotated, in the direction shown by arrow C in FIG. 9, suchat axis X4 is rotated relative to axis X1. Dilator 80 is rotatedsubstantially 90 degrees, as shown in FIGS. 10-12, such that axis X4 issubstantially perpendicular to axis X1 to displace and space psoasmuscle P and/or tissue posteriorly relative to vertebrae V and loosenits attachments to vertebrae V. Rotation of dilator 80 causes surface 84to apply pressure against psoas muscle P to sweep psoas muscle Pposteriorly relative to the spine. Dilator 80 is rotated 90 degrees, inthe direction shown by arrow 3 in FIGS. 13 and 14, such that dilator 80returns to the initial position and axes X1, X4 are aligned.

Retractor 12 is disposed in a closed configuration in a position, asshown in FIGS. 15 and 16, such that blades 14, 16 form cavity 40 and areintroduced along an oblique trajectory along surgical pathway PX. In oneembodiment, retractor 12 is manipulated such that dilator 80 is disposedwith cavity 40 by a practitioner holding handle 50 with a right hand.Retractor 12 is inserted over dilators 80, 94 and positioned adjacentvertebrae V1, V2 such that axes X1, X2 are disposed in alignment. Insome embodiments, retractor 12 can be locked in a closed configurationwith ratchet 60, as described herein.

Retractor 12 is rotated, in the direction shown by arrow E in FIG. 18,approximately 90 degrees into a position, as shown in FIGS, 17-19, suchthat blades 14, 16 displace and space psoas muscle P and/or tissueposteriorly relative to vertebrae V and loosen its attachments tovertebrae V. Blades 14, 16 are rotated substantially 90 degrees and suchrotation causes axes X2, X4 to rotate relative to axis X1 Rotation ofblades 14, 18 causes surfaces 20, 32 to apply pressure against psoasmuscle P to sweep psoas muscle posteriorly relative to the spine.

Retractor 12 is manipulated, which may include releasing ratchet 60 froma locked orientation, from the closed configuration such that blades 14,16 are rotated, in the direction shown by arrows F in FIG. 20, todispose retractor 12 in an open configuration, as shown in FIGS. 20-22.Dilators 80, 94 are removed. In some embodiments, blade 14 is a cephaladblade and pinned to vertebra V2 via a pin hole 97 to stabilize retractor12 with vertebrae V. Blades 14, 16 are spaced to define a workingchannel 40 a aligned with surgical pathway PX to facilitate introductionof implants, constructs and/or surgical instrumentation, as describedherein, along an oblique trajectory along surgical pathway PX.

In one embodiment, a flex arm 100 is connected with handle 50 tostabilize retractor 12 by connecting retractor 12 to a surgical table,as shown in FIG. 22. In some embodiments, OLIF light cables (not shown)are disposed with blades 14, 16, via openings 102 and the cables arerouted around bosses 104.

In some embodiments, a discectomy is performed via surgical pathway PXwith channel 40 a of retractor 12. In some embodiments, instruments,such as, for example, a Cobb, mallet, shaver, serrated curettes, rasp, aring curette, a uterine curette and/or combo tools are utilized toperform a discectomy of the disc space. In some embodiments, theinstruments enter the subject body obliquely through retractor 12 andcan be turned orthogonally to allow the surgeon to work orthogonallyacross the disc space. The disc space is distracted until adequate discspace height is obtained.

In some embodiments, an anterior longitudinal ligament (ALL) releaseprocedure can be performed using an OLIF approach post-discectomy. Forexample, loosening the ALL can be performed by placing holes or partialcuts in the ALL such that the OLIF surgical pathway is immediatelycloser to the ALL.

In some embodiments, trial implants (not shown) are delivered alongsurgical pathway PX and channel 40 a of retractor 12. The trial implantsare used to distract one or more intervertebral spaces of the L2-L5vertebral levels and apply appropriate tension in the intervertebralspace allowing for indirect decompression. In one embodiment, a directdecompression of the disc space is performed by removing a portion of aherniated disc. In some embodiments, one or a plurality of interbodyimplants can be introduced and delivered along surgical pathway PX andchannel 40 a for implantation with one or more intervertebral spaces ofthe L2-L5 vertebral levels.

In some embodiments, pilot holes or the like are made in vertebrae V1,V2 adjacent its intervertebral space, via surgical pathway PX andchannel 40 a for receiving bone fasteners and/or attaching spinalconstructs, which may include rods and plates. An inserter is attachedwith the implants and/or spinal constructs for delivery along surgicalpathway PX and channel 40 a adjacent to a surgical site for implantationadjacent one or more vertebra and/or intervertebral spaces of the L2-L5vertebral levels.

Upon completion of a procedure, as described herein, the surgicalinstruments, assessmblies and non-implanted components of spinal implantsystem 10 are removed and the incision(s) are closed. One or more of thecomponents of spinal implant system 10 can be made of radiolucentmaterials such as polymers. Radiopaque markers may be included foridentification under x-ray, fluoroscopy, CT or other imaging techniques.In some embodiments, the use of surgical navigation, microsurgical andimage guided technologies, as described herein, may be employed toaccess, view and repair spinal deterioration or damage, with the aid ofspinal implant system 10. In some embodiments, spinal implant system 10may include implants and/or spinal constructs, which may include one ora plurality of plates, rods, connectors and/or bone fasteners for usewith a single vertebral level or a plurality of vertebral levels.

In one embodiment, spinal implant system 10 includes an agent, which maybe disposed, packed, coated or layered within, on or about thecomponents and/or surfaces of spinal implant system 10. In someembodiments, the agent may include bone growth promoting material, suchas, for example, bone graft allograft, xenograft, autograft, bone paste,bone chips, Skelite®, and/or BMP to enhance fixation of the componentsand/or surfaces of spinal implant system 10 with vertebrae. In someembodiments, the agent may include one or a plurality of therapeuticagents and/or pharmacological agents for release, including sustainedrelease, to treat, for example, pain, inflammation and degeneration. Insuch embodiments, titanium coatings may be applied via a variety ofmethods, including but not limited to plasma spray coating and/ormechanical attachment of titanium plates to form a PEEK/Titaniumimplant.

In one embodiment, as shown in FIGS. 23-27 spinal implant system 10,similar to the systems and methods described herein, comprises retractor12 described herein, having blades 214, 216 similar to blades 14, 16described herein. Blade 214 extends between an end 214 a and an end 214b. Blade 214 includes an inner surface 218 and an outer surface 220configured for engagement with tissue, similar to that discussed withregard to the embodiments described herein. Surface 218 defines a matingelement, such as, for example, a longitudinal groove 240 extendingbetween ends 214 a, 214 b. Groove 240 comprises a uniformly configuredchannel disposed in substantially co-axial or parallel alignment with alongitudinal axis of blade 214. In some embodiments, groove 240 mayextend along all or only a portion of surface 218. In some embodiments,groove 240 may extend in alternate orientations relative to alongitudinal axis of blade 214, such as, for example, transverse,angular, offset and/or staggered. Blade 214 includes pin hole 297,similar to pin hole 97 described herein. In some embodiments, pin hole297 is disposed with a superior blade and adjacent an edge surface ofthe blade.

Blade 216 extends between an end 216 a and an end 216 b. Blade 216includes an inner surface 230 and an outer surface 232 configured forengagement with tissue, similar to that discussed with regard to theembodiments described herein. Surface 230 defines a mating element, suchas, for example, a longitudinal groove 242 extending between ends 216 a,216 b. Groove 242 comprises a uniformly configured channel disposed insubstantially coaxial or parallel alignment with a longitudinal axis ofblade 216. In some embodiments, groove 242 may extend along all or onlya portion of surface 230. In some embodiments, groove 242 may extend inalternate orientations relative to a longitudinal axis of blade 216,such as, for example, transverse, angular, offset and/or staggered.

Grooves 240, 242 are configured to receive a member, such as, forexample, a blade 302, which is an independent component of system 10 andseparately attachable with retractor 12 in an interlockingconfiguration. In one embodiment, blade 302 is interlocked with blades214, 216 in a dovetail connection. In some embodiments, in an openconfiguration of blades 214, 216, similar to and as described hereinwith regard to blades 14, 16, groove 240 is spaced from groove 242, asshown in FIG. 23.

Blade 302 is oriented for alignment with blades 214, 216 and grooves240, 242, as shown in FIG. 24, Mating elements, such as, for example,flanges 304, disposed on sides of blade 302, are oriented for alignmentwith grooves 240, 242. Flanges 304 are manipulated for slidableengagement with surfaces 218, 230 such that blade 302 axially translatesrelative to blades 214, 216 for assembly with retractor 12, as shown inFIG. 25.

Blade 302 is selectively translated relative to blades 214, 216 and inan interlocking configuration with grooves 240, 242 to partially closeand/or fully close a gap G1 of blades 214, 216. In some embodiments,blade 302 is adjustable to partially close gap G1, as shown in FIG. 25.In some embodiments, blade 302 is disposed in alignment with the ends ofblades 214, 216 to fully close gap G1, as shown in FIG. 26. In someembodiments, disposal of blade 302 with blades 214, 216 partiallyencloses a surgical pathway, as described for example, in connectionwith use of retractor 12 herein. In some embodiments, blade 302 may bedisposed with blades 214, 216, as described herein, in various surgicalapproaches to the spine, including anterior, posterior, posteriormid-line, direct lateral, postero-lateral, and/or antero-lateralapproaches, and in other body regions, to partially dose or fully dosegap G1 and/or partially enclose a surgical pathway.

In some embodiments, grooves 240, 242 are disposed adjacent to ananterior portion of blades 214, 216 relative to an orientation ofretractor 12 with a surgical site and/or vertebrae, see, for example,that shown with regard to FIGS. 20 and 21. This configuration orientsblade 302 with blades 214, 216 to close an anterior gap and/ opening,such as, for example, gap G1 between blades 214, 216. In someembodiments, groove 240 and/or groove 242 may be variously disposed withblades 214, 216. In some embodiments, blade 302 may be variouslyconfigured and dimensioned to accommodate variously configured anddimensioned retractor gaps and/or openings.

In one embodiment, as shown in FIGS. 28-31, retractor 12 includes blades214, 216, described with regard to FIGS. 23-27. having blade 302disposed with grooves 240, 242 and a blade 502. Surface 218 includesgroove 240, described herein, and defines a mating element, such as, forexample, a longitudinal groove 440 spaced from groove 240 and extendingbetween ends 214 a, 214 b. Groove 440 comprises a uniformly configuredchannel disposed in substantially co-axial or parallel alignment with alongitudinal axis of blade 214. In some embodiments, groove 440 mayextend along all or only a portion of surface 218. In some embodiments,groove 440 may extend in alternate orientations relative to alongitudinal axis of blade 214, such as, for example, transverse,angular, offset and/or staggered.

Surface 230 includes groove 242, described herein, and defines a matingelement, such as, for example, a longitudinal groove 442 spaced fromgroove 242 and extending between ends 216 a, 216 b. Groove 442 comprisesa uniformly configured channel disposed in substantially co-axial orparallel alignment with a longitudinal axis of blade 216. In someembodiments, groove 442 may extend along all or only a portion ofsurface 230. In some embodiments, groove 442 may extend in alternateorientations relative to a longitudinal axis of blade 216, such as, forexample, transverse, angular, offset and/or staggered.

Grooves 440, 442 are configured to receive a member, such as, forexample, blade 502, which is an independent component of system 10 andseparately attachable with retractor 12 it an interlockingconfiguration. In one embodiment, blade 502 is interlocked with blades214, 216 in a dovetail connection. In some embodiments, in an openconfiguration of blades 214, 216, similar to and as described hereinwith regard to blades 14, 16, groove 440 is spaced from groove 442, asshown in FIG. 28.

Blade 502 is oriented for alignment with blades 214, 216 and grooves440, 442, as shown in FIG. 28. Mating elements, such as, for example,flanges 504, disposed on sides of blade 502, are oriented for alignmentwith grooves 440, 442. Flanges 504 are manipulated for slidableengagement with surfaces 218, 230 such that blade 502 axially translatesrelative to blades 214, 216 for assembly with retractor 12, as shown inFIG. 29.

Blade 502 is selectively translated relative to blades 214, 216 and inan interlocking configuration with grooves 440, 442 to partially closeand/or fully close a gap G2 of blades 214, 216, In some embodiments,blade 502 is adjustable to partially close gap G2, as shown in FIG. 29.In some embodiments, blade 502 is disposed in alignment with the ends ofblades 214, 216 to fully close gap G2, as shown in FIG. 30. In someembodiments, disposal of blade 502 with blades 214, 216 partiallyencloses a surgical pathway, as described for example, in connectionwith use of retractor 12 herein. In some embodiments, disposal of blades302, 502 with blades 214, 216, as described herein, fully encloses asurgical pathway. In some embodiments, blade 502 may be disposed withblades 214, 216, as described herein, in various surgical approaches tothe spine, including anterior, posterior, posterior mid-line, directlateral, postero-lateral, and/or antero-lateral approaches, and in otherbody regions, to partially close or fully close gap G2 and/or partiallyor fully enclose a surgical pathway.

In some embodiments, grooves 240, 242 are disposed adjacent to ananterior portion of blades 214, 216 and grooves 440, 442 are disposedadjacent to a posterior portion of blades 214, 216 relative to anorientation of retractor 12 with a surgical site and/or vertebrae, see,for example, that shown with regard to FIGS. 20 and 21. Thisconfiguration orients blade 302 with blades 214, 216 to close ananterior gap and/or opening, such as, for example, gap G1 between blades214, 216 and orients blade 502 with blades 214, 216 to close a posteriorgap and/or opening, such as, for example, gap G2 between blades 214,216. In some embodiments, this orientation of blades 302, 502 withblades 214, 216 forms a completely enclosed tube of retractor 12 tofully enclose a surgical pathway. In some embodiments, groove 440 and/orgroove 442 may be variously disposed with blades 214, 216. In someembodiments, blade 502 may be variously configured and dimensioned toaccommodate variously configured and dimensioned retractor gaps and/oropenings. In some embodiments, the mating elements may include key andslot elements, dips, latches, friction fit elements, pressure fitelements and/or adhesive elements.

It will be understood that various modifications and/or combinations maybe made to the embodiments disclosed herein. Therefore, the abovedescription should not be construed as limiting, but merely asexemplification of the various embodiments. Those skilled in the artwill envision other modifications within the scope and spirit of theclaims appended hereto.

What is claimed is:
 1. A method for treating a spine, the methodcomprising the steps of: providing a surgical instrument comprisingfirst and second members, the first member being integrally formed witha first handle portion and the second member being integrally formedwith a second handle portion, the surgical instrument comprising a pinthat extends through the first handle portion and the second handleportion to allow the first member to rotate relative to the secondmember about the pin, the first member being rotatable relative to thesecond member to define an opening and space tissue adjacent the spine,each member having an inner surface that defines a mating element and anouter surface being engageable with the tissue, the surgical instrumentfurther comprising at least one third element defining a mating element;engaging the mating elements to dispose the at least one third elementwithin the opening; and selectively translating the at least one thirdelement relative to the first member and the second member to at leastpartially close the opening.
 2. A method as recited in claim 1, whereinthe opening comprises an anterior gap.
 3. A method as recited in claim1, wherein the at least one third element comprises an anterior bladeand a posterior blade, the blades being disposed with the first memberand the second member to fully enclose a surgical pathway.
 4. A methodas recited in claim 1, wherein the mating elements defined by the innersurfaces of the members are longitudinal grooves and the mating elementof the at least one third element is a pair of flanges, each of theflanges being disposed in one of the grooves as the at least one thirdelement translates relative to the members.
 5. A method as recited inclaim 1, wherein the mating elements defined by the inner surfaces ofthe members are a pair of anterior grooves and a pair of posteriorgrooves, the at least one third element comprising a first blade that ispositioned within the anterior grooves and a second blade that ispositioned within the posterior grooves when the mating elements engage.6. A method as recited in claim 5, wherein the first blade is spacedapart from the second blade by the inner surfaces.
 7. A method asrecited in claim 1, further comprising pivoting the first memberrelative to the second member about a pin that extends through themembers to increase a width of the opening before engaging the matingelements.
 8. A method as recited in claim 1, further comprising pivotingthe first member relative to the second member such that the outersurfaces engage the tissue and the members push the tissue apart beforeengaging the mating elements.
 9. A method as recited in claim 1, furthercomprising inserting a pin through a pin hole of one of the members andinto the spine, the pin hole extending through a wall of one of themembers to stabilize the surgical instrument with the spine.
 10. Amethod as recited in claim 1, wherein the first member includes oppositefirst and second end surfaces, the second member including oppositethird and fourth end surfaces, the first member being rotatable relativeto the second member such that the first end surface is spaced apart afirst distance apart from the third end surface and the second endsurface is spaced a second distance apart from the fourth end surface,the second distance being greater than the first distance.
 11. A methodfor treating a spine of a patient, comprising: inserting a retractorwithin the patient such that outer surfaces of first and second bladesof the retractor engage tissue adjacent to the spine; pivoting a firstblade relative to the second blade such that the outer surfaces push thetissue apart and a gap between the blades increases in width; insertinga third blade into grooves of the first and second blades; translatingthe third blade within the grooves to at least partially close the gap;inserting a first dilator into the tissue; and inserting a seconddilator over the first dilator, wherein the second dilator is insertedsuch that a major axis of the second dilator is aligned with alongitudinal axis defined by the spine, and wherein the method furthercomprises rotating the second dilator such that the major axis issubstantially perpendicular to the longitudinal axis to displace thetissue.
 12. A method as recited in claim 11, wherein the first bladeextends along a first longitudinal axis between a first end and a secondend and the second blade extends along a second longitudinal axisbetween a first end and a second end, the groove in the first bladeextending parallel to the first longitudinal axis and the groove in thesecond blade extending parallel to the second longitudinal axis.
 13. Amethod as recited in claim 11, wherein the grooves are uniformlyconfigured.
 14. A method as recited in claim 11, wherein: the firstblade comprises a second groove that is spaced apart from the groove inthe first blade, the second blade comprises a second groove that isspaced apart from the groove in the second blade, and the retractorcomprises a second gap between the first and second blades, the secondgap being spaced apart from the gap; and the method further comprisesinserting a fourth blade into the second grooves and translating thefourth blade within the second grooves to at least partially close thesecond gap.
 15. A method as recited in claim 11, wherein the retractoris inserted along an oblique surgical pathway.
 16. A method as recitedin claim 11, further comprising rotating the second dilator 90 degreessuch that the major axis is aligned with the longitudinal axis, theretractor being inserted after the second dilator is rotated 90 degreessuch that the dilators are positioned between the first blade and thesecond blade.
 17. A method as recited in claim 11, wherein: theretractor comprises a ratchet; and the method further moving the ratchetfrom a locked orientation in which the first and second blades areprevented from pivoting relative to one another to an unlockedorientation in which the first and second blades are pivotable relativeto one another.
 18. A method as recited in claim 11, further comprisingperforming a discectomy via a surgical pathway defined by the blades.19. A method for treating a spine of a patient, comprising: positioningthe patient on their side; inserting a first dilator into tissueadjacent the spine along an oblique trajectory; inserting a seconddilator over the first dilator such that a major axis of the seconddilator is aligned with a longitudinal axis defined by the spine;rotating the second dilator 90 degrees such that the major axis issubstantially perpendicular to the longitudinal axis to displace thetissue; inserting a retractor along the oblique trajectory over thesecond dilator such that outer surfaces of first and second blades ofthe retractor engage the tissue; moving a ratchet of the retractor froma locked orientation in which the first and second blades are preventedfrom pivoting relative to one another to an unlocked orientation inwhich the first and second blades are pivotable relative to one another;pivoting a first blade relative to the second blade about a pin thatextends through the first and second blades such that the outer surfacespush the tissue apart; inserting a third blade into grooves of the firstand second blades; translating the third blade within the grooves to atleast partially close a first gap between the first and second blades;inserting a fourth blade into second grooves of the first and secondblades; translating the fourth blade within the second grooves to atleast partially close a second gap between the first and second blades;and performing a discectomy via a surgical pathway defined by theblades.